Solve for $x$ : $3x - 9 = 7x + 4$
Answer: Subtract $3x$ from both sides: $(3x - 9) - 3x = (7x + 4) - 3x$ $-9 = 4x + 4$ Subtract $4$ from both sides: $-9 - 4 = (4x + 4) - 4$ $-13 = 4x$ Divide both sides by $4$ $\dfrac{-13}{4} = \dfrac{4x}{4}$ Simplify. $-\dfrac{13}{4} = x$